Electric furnace



Sept. 1, 1925.

1,552,142 J. H. GRAY ELECTRIC FURNACE Filed Nov. 11, 1920 3 Sheets-Sheet l INVENTOR Q J MES HGRHT %we r [L V W1 Sept. 1, 1925.

J. H. GRAY ELECTRI C FURNACE Filed Nov.

INVENTOR RHY 11, 1920 I5 Sheets-Sheet 2 AT ORNEY Sept. 1, 1925. 1,552,142

J. H. GRAY ELECTRI C FURNACE Filed Nov. 11, 1920 3 Sheets-Sheet 5 \NVENTOR Patented Sept. 1 1925.

UNITED STATES Turns 11. army, or rmw Yo-nx, N. Y.

ELECTRIC FURNACE.

Application filed November 11, 1920. Serial No. 423,221.

To all whom it may concern:

Be it known that I, JAMES H. GRAY, a citizen of the United. States, residing in the city, county, and State of New v York, have 6 invented certain new and useful Improvements in Electric Furnaces, of which the following is a specification.

This invention aims to provide certain improvements which render electric fur 10 naces more efiicient and economical in operation.

The accompanying drawings illustrate a furnace embodying the invention.

Fig. 1 is a side elevation thereof; Fig. 2 is a plan and Fig. 3 is a rear elevation;

Fig. 2 is a diagrammatic perspective showing the cable for raising one electrode holder and bus bar.

The vessel or crucible 1 which constitutes the furnace proper is circular in plan and is mounted on rockers 2 which rest on roller bearings 3 mounted on trunnions 4 on a base 5. The furnace is tilted by means of links 6 connected to crank pins on bull wheels or 25 gears 7 which are driven, through suitable intermediate gearing, from a motor 8. The tilting gearing rears n the same foundation 9 on which the supporting base is carried, the tilting mechanism being arranged at the front of the furnace, as the side on which the workmen operate is usually called. This arrangement allows the bringing of the furnace bottom as low as possible so as to save head room, which is important especially in the larger sizes of furnace. The center on which the furnace turns is above the supporting rockers, and the links 6 are subject ed to a pulling or tensile strain in tilting the furnace which is the heaviest part of its work, the furnace being generally empty when it is to be returned to its upright position. 1

The arrangement for supporting the crucible of the furnace on the rockers is also very simple and compact. The upper faces of the rockers are provided with oblique flat end portions 10 and a central horizontal portion ll'recessed to accommodate cross-beams 12 extendin across the space between the rockers and eyond them asshown in Fig. 3 under the overhanging sides of the vessel 1, The rockers are also connected to each other by means of webbed braces 13 and 14 at intervals in their lengths. The bottom of the vessel 1 is shaped with flat faces to bear on the cross-beams 12 and on the oblique faces 10 of the rockers. This gives a low firm mountin of the vessel on the rockers, its principa weight being carried on the central portion of the latter, through the crossbeams 12.

The vessel is provided with a spout 15 on the rearward side and with doors 16 for charging and inspection at other points in its circumference, with the usual means for opening and closing such doors. Threeelectrodes 17 are provided, assuming the furnace to be operated by the usual three-phase alternating current. Brackets 18 and v1S) are mounted on a' ring surrounding the base of the vessel, the former carrying columns 20 and the latter carrying columns 21, the columns serving to support an overhead platform indicated as a whole. by the numeral 22. This overhead platform carries three electric motors and, winches 23 driven therefrom, each winch serving to operate a cable 24 which controls the raising and lowering of one of the electrodes. As shown, for example, in Fig. 2, the cable 24 runs over a pulley block.25 and back to a fixed point of the winch. The block 25 is connected to an equalizing lever 26 from which three cables run forward. The central cable 27 runs over a fixed guide pulley 28 in a vertical plane and back over a second fixed pulley 29 and down to the rear end of an arm 30 which extends rearwardly from the electrode clamp and constitutes in eflectpart of the electrode holder. Other cables 31 run from the equalizing lever 26 ver horizontal guide pulleys 32 and thence over guide pulleys 33 set in oblique vertical planes, whence the cables 31 extend down to the sides of the clamping members 34 of the electrodes, one on each side. Thus we get a straight pull on the arm 30 of the holder and on the electric cable 35 which is connected to its rear end, and we get an equalized pull on the two sides of the electrodes.

The described arrangement for the electrode-operati'ng mechanism has several other advantages. The mounting of the winches on top leave room for an extra side door 16 as shown in Fig. 1. It also leaves an abundant space at the side for the cables 35 which is particularly important in the case of large furnaces. It provides a single space, the width of which is indicated at 36, Fig. 1, between the columns 20 and 21 on one side and the corresponding columns on the other side, through which space all the electrical connections or buses pass. It is a problem in designing large furnaces of this character to secure counectlons from the furnace to the transformer or other source of current which will carry the great quantity of current required, or which will carry it without too great losses. The 111- terposition of metal parts between the connections to the several electrodes sets up a reactance which seriously limits the supply of current. Nevertheless it is necessary to mount various parts of the apparatus at the side of the furnace and in previous constructions these have generally been disadvantageous for the reasons stated. By mounting all this mechanism overhead and by providing a single clear space through which the three electrical connections pass I have secured a very much increased efiiciency and can design the furnace for a great capacity.

Each electrode holder is provided at the rear with a guide post 37 Which passes up through a guide 38 (F ig. 2) formlng part of the overhead structure. This enables the holders to carry part of the sidewise strain induced by the weight of the electrodes when the furnace is tilted and thus relieves the furnace roof and cooling rings of a great part of such strain.

The holders 30 for the electrodes are hollow and are kept cool by a circulation of water therethrough. Fig. 2 shows an opening 39 to which is connected a flexible interwater pipe 40, Fig. 3. The outer end of each holder 80 is open and connected to a flexible outlet Water pipe 41.

Though I have described with great particularity .of detail a certain embodiment of my invention, yet it is not to be understood therefrom that the invention is restricted to the particular embodiment illustrated. Various modifications thereof in detail and in the arrangement of the parts may be made by those skilled in the art without departing from the invention as defined in the followin claims.

Vhat I claim is 1. A tilting electric furnace having electrodes extending through the roof thereof and tilting mechanism located at one side of the vertical space occupied by the furnace comprising an electric motor, a bull wheel connected by a substantially horizontal link with the furnace and reduction gearing for transmittin the power from said motor to said bull wheel.

2. A tilting electric furnace having winches for adjusting the electrodes, holders comprising an arm and 'a clamp for the electrodes, said winches being mounted above and movable with the furnace and above the electric connections of the electrodes and cables connecting said holders with said winches and arranged to produce an equalized straight pull on said holders.

3. A tilting electric furnace having an overhead platform carrying mechanism for adjusting the electrodes and columns mounted on the furnace and supporting said overhead platform, said columns being arranged with a single open space and means extending through said open space above the furnace and carrying all the electrical. connections to the electrodes.

4. Atilting electric furnace having adjustable electrodes, a holder comprising an arm and clamp for each electrode said holder be ing movable with the furnace and adjusting cables engaging the clamp at opposite sides of the electrode and engaging the arm to produce a straight pull on the latter and an equalized pull on the two sides of the electrode.

5. A tilting electric furnace having elec trodes passing through the roof, an overhead structure movable with the furnace, holders for said electrodes extending from one side and across to the center of the furnace and suspended by cables from said overhead structure, and members secured to said holders engaging guides in said overhead structure for transn'iitting to the latter a part of the sidewise strain due to the weight of the electrodes when the furnace is tilted.

6. A. tilting .electric furnace having electrodes passing through the roof, a rigid overhead structure supported by uprights secured to opposite sides of the furnace and movable therewith, holders for said electrodes comprising an arm and a clamp suspended from said structure, said arm being provided with flexible connections whereby a cooling medium can be circulated in intimate contact throughout the entire length of the arm regardless of its inclination or elevation.

In witness whereof, I have hereunto signed my name.

JAMES H. GRAY. 

